Recently, along with diversification of food materials, a demand for the increase of a capacity of an indoor volume of a refrigeration device such as a household-use electric freezer refrigerator is increasing. To cope with such a demand, improvement has been made to increase capacity of a household-use electric refrigerator while maintaining a size of an external appearance of the household-use electric refrigerator. As one of methods for increasing the indoor volume, the reduction in size of a machine compartment which houses a sealed compressor has been in progress. In the sealed compressor used in the household-use electric freezer refrigerator, other refrigeration cycle devices and the like, the miniaturization and the reduction in height of the sealed compressor have been strongly required.
Under such a situation, among conventional sealed compressors, there has been known a sealed compressor which uses an outer-rotor-type DC motor in place of an inner-rotor-type DC motor (see Patent Literature 1, for example). The inner-rotor-type DC motor is configured such that a rotor rotates in the inside of a stator which forms an electrically-operated element. The outer-rotor-type DC motor where a rotor rotates outside a stator is provided for miniaturization and lowering of a height of the sealed compressor. Accordingly, the outer-rotor-type DC motor is suitable for miniaturization and the reduction of a thickness of the sealed compressor.
FIG. 5 is a side view showing a bearing mechanism and an electrically-operated element of a conventional sealed compressor.
As shown in FIG. 5, bearing mechanism 402 of the conventional sealed compressor includes: shaft 408 which includes main shaft 404 and eccentric shaft 406; and bearing 410 which pivotally supports main shaft 404. Sliding portions 412, 414 are formed on an outer periphery of main shaft 404 and an inner periphery of bearing 410, respectively.
Non-sliding portion 415 where an inner diameter is increased is formed on a portion of sliding portion 414 of bearing 410.
Electrically-operated element 418 is an outer-rotor-type DC motor formed of: stator 420; and rotor 422 disposed coaxially with stator 420. Rotor 422 is disposed so as to surround a periphery of stator 420.
Stator 420 is fixed to outer peripheral portion 423 of bearing 410 by press-fitting or the like. Sliding portion 414 is disposed on an inner periphery of bearing 410 at a position where stator 420 is fixed.
In rotor 422, permanent magnet 428 is disposed on outer peripheral end portion 426 of disc-like frame 424. Rotor 422 is fixed by shrinkage fitting or the like to an outer periphery of a lower end of shaft 408 at circular cylindrical rotor shaft hole 430 formed at a center of frame 424.
However, in the conventional sealed compressor, stator 420 is fixed to outer peripheral portion 423 of bearing 410 by press-fitting or the like. Accordingly, the conventional sealed compressor has a drawback that an inner peripheral surface of bearing 410 at the position where stator 420 is fixed is deformed and hence, solid contact occurs between the inner peripheral surface of bearing 410 and sliding portion 412 of main shaft 404 whereby the inner peripheral surface of bearing 410 is liable to wear.